Next crop of Covid-19 vaccine developers take more traditional route

The handful of drugmakers dominating the global coronavirus vaccine race are pushing the boundaries of vaccine technology. The next cr op under development features more conventional, proven designs.

The world will need several dif ferent vaccines to fight the Covid19 pandemic, given the sheer size of global need, variations in ef fects on different populations, and possible limits of effectiveness in the first crop. Many leading candidates now in finalstage testing are based on new, largely unproven technology platforms designed to produce vaccines at speed. They include messenger RNA (mRNA) technology used by Moderna Inc. and Pfizer Inc. with partner BioNTech SE, and inactivated cold virus platf orms used by Oxford University/AstraZeneca Plc, Johnson & Johnson and CanSino Biologics, whose vaccine has been ap proved for military use in China. Merck & Co. in September started testing a Covid19 vaccine based on a weakened measles virus that delivers genes from the new coronavirus into the body to stimulate an immune response to the coronavirus. Of these, only the technology offered by J&J and CanSino that use cold viruses as vectors to deliver coronavirus genetic material have ever produced a licensed vaccine – for Ebola.

The next set of candidates –with latestage trial results expected in the first half of 2021 – are heavily skewed toward approaches that have produced successful vaccines. Conventional methods include using a killed or inactivated version of the pathogen that causes a disease to provoke an immune response, such as those used to make flu, polio and rabies vaccines.

Also more common are proteinbased vaccines that use purified pieces of the virus to spur an immune response. Vaccines against whooping cough, or pertussis, and shingles employ this approach.

French drugmaker Sanofi is developing a proteinbased Covid19 vaccine employing the same approach it uses for its Flublok seasonal flu vaccine. Sanofi expects to start the final phase of testing in early December, with approval targeted in the first half of 2021.

While Novavax Inc. has not yet produced a li censed vaccine, it is using similar purified protein technology and expects to start a late stage US tr ial involving 30,000 volunteers in late November.

“Those are more traditional approaches, so we can feel more comfortable that we have a lot of experience with them,” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. Offit also sees promise in some of the inactivated virus vaccines being developed by Chinese researchers, including Sinopharm’s China National Biotec Group (CNBG), one of the f ew firstcrop developers using a traditional technique.

Other secondwave developers are making vac cines based on virus like particles (VLPs), which mimic the structure of the coronavirus but contain no genetic material from it. VLP vaccines can be produced in a variety of different types of cells, including mammal, bacterial, insect, yeast and plant cells.